1. Field of the Invention
The present invention relates to an inverted pendulum type moving body and a method of controlling the same.
2. Description of Related Art
An inverted pendulum type moving body travels on a plain surface while being maintained in an inverted state. In this case, the inverted pendulum type moving body drives left and right driving wheels to control the moving body to be maintained in the inverted state by correcting the position of the center of mass of the body so that the position of the center of mass is positioned vertically upward of an axle. For example, Japanese Unexamined Patent Application Publication No. 2005-145293 (Kaneko et al.) discloses a technology in which an inverted two-wheel carriage robot, which includes a control system that integrally performs inversion control and position control, is allowed to travel along a path set in advance.
When the inverted pendulum type moving body collides with an obstacle during traveling and cannot cross over the obstacle, the wheels cannot be driven in a traveling direction any more. As a result, when the moving body collides with the obstacle, a force (impact reaction) is generated in a direction opposite to the traveling direction of the wheels. When the wheels stop rotating due to the impact reaction, a force for driving the wheels is applied to the body as a drive reaction, and the drive reaction causes the body of the inverted pendulum type moving body to rotate significantly backward. In this case, in the conventional inverted pendulum type moving body, the wheels are driven in the direction opposite to the traveling direction (that is, backward) so that the position of the center of mass of the body, which rotates backward, is located vertically upward of the axle, thereby maintaining the moving body in the inverted state.
In this case, however, when the wheels are driven backward so as to maintain the moving body in the inverted state, a forward torque is generated with respect to the body. As a result, the inverted pendulum type moving body further drives the wheels forward so that forward rotation of the body is cancelled out, to thereby maintain the moving body in the inverted state. Thus, the inverted pendulum type moving body receives the torque in a front-back direction due to a disturbance caused by a contact with an obstacle, and then swings significantly in the front-back direction so as to maintain the moving body in the inverted state against the disturbance. For this reason, a passenger of the inverted pendulum type moving body is caused to swing significantly in the front-back direction. In particular, because a backside area is a dead area for the passenger, the backward swing gives the passenger an extremely uneasy feeling. Further, because the moving body cannot be maintained in the inverted state depending on the magnitude of the impact, the backward swing is dangerous.
Meanwhile, Japanese Patent Translation Publication No. 2003-508285 (Dean L. Kamen et al.) discloses an inverted pendulum type moving body that performs inverted control using a control arm.
The technology disclosed in Dean L. Kamen et al. enables stable control of the inverted pendulum type moving body by supporting a passenger with the control arm, but has a problem in that it is difficult for the moving body to avoid an obstacle safely when the moving body collides with an obstacle.
The present invention has been made to solve the above-mentioned problems, and therefore an object of the present invention is to provide an inverted pendulum type moving body capable of avoiding an obstacle safely when the inverted pendulum type moving body comes into contact with an obstacle, and a method of controlling the same.